Evolution of Germline-Limited Sequences in Two Populations of the Ciliate Chilodonella uncinata
Evolution of Germline-Limited Sequences in Two Populations of the Ciliate Chilodonella uncinata
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DOI：
10.1007/s00239-012-9493-4
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发表时间：
2012-03
影响因子：
3.9
通讯作者：
R. Zufall;Mariel Sturm;Brian C. Mahon
中科院分区：
文献类型：
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作者：
R. Zufall;Mariel Sturm;Brian C. Mahon
纤毛虫是一种微生物真核生物，其核功能分为种系微核和体细胞宏核。在巨核发育过程中，基因组经历了一系列的重组事件，其中包括对中间DNA的精确切除。在这里，我们确定了纤毛虫微核和宏核基因组中四个位点的结构，并比较了其中两个位点上微核受限序列和宏核目标序列的变异水平。我们发现，在一个种群中，生殖系限制序列的进化速度与其他假定的中性位点相同，但在种群之间，生殖系限制序列的突变积累速度要比其他位点快得多。我们还发现了大核重组和不完全消除干预DNA的证据，这导致了大核基因组多样性的增加。我们的研究结果支持了纤毛虫不寻常的基因组特征可以导致快速和不可预测的多样化模式的断言。
Ciliates are microbial eukaryotes that separate their nuclear functions into a germline micronucleus and a somatic macronucleus. During development of the macronucleus the genome undergoes a series of reorganization events that includes the precise excision of intervening DNA. Here, we determine the architecture of four loci in the micronuclear and macronuclear genomes of the ciliateChilodonella uncinataand compare the levels of variation in micronuclear-limited sequences to macronuclear destined sequences at two of these loci. We find that within a population, germline-limited sequences are evolving at the same rate as other putatively neutral sites, but between populations germline-limited sequences are accumulating mutations at a much faster rate than other sites. We also find evidence of macronuclear recombination and incomplete elimination of intervening DNA, which result in increased diversity in the macronuclear genome. Our results support the assertion that the unusual genomic features of ciliates can result in rapid and unpredicted patterns of diversification.